South Australia (SA1) experienced sustained negative pricing over three intervals on 17 September 2026, with prices reaching a minimum of -$7.36/MWh around 05:10. The region had strong solar generation (155 MW) and moderate wind (37 MW) concurrent with gas-fired generation (82 MW CCGT, 0.11 MW OCGT) during an off-peak morning period.
The negative pricing was driven by a binding constraint (F_T+LREG_0050) with marginal values ranging from 23–31 $/MWh, indicating a physical limitation in the network requiring additional generation dispatch to resolve. With high renewable generation and low morning demand, the constraint-driven requirement to increase generation output pushed prices negative, forcing generators to accept negative prices to meet the binding constraint obligation.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.